<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="app">
    <h2>{{counter}}</h2>
<!--    <button v-on:click="counter++">+</button>-->
<!--    <button v-on:click="counter&#45;&#45;">-</button>-->

<!--    <button v-on:click="add">+</button>-->
<!--    <button v-on:click="decrement">-</button>-->

    <!--    v-on的语法糖-->
    <button @click="add">+</button>
    <button @click="decrement">-</button>

</div>

<script src="../js/vue.js"></script>
<script>
    const  app = new Vue({
      el:'#app',
      data:{
        counter: 0
      },
      methods:{
          add(){
              return  this.counter++
          },
          decrement(){
              return this.counter--
          }
      }
    })

</script>
</body>
</html>